Hi, I usually have normal periods. I was suppose to start on Oct 17th but didn't start until oct 20th. I didn't really have a period just a pink and brown discharge for 7 days now and an small amount of blood on the 3rd or 4th day. I had a flu shot on the 18th. Could this be the problem? I have also been unusally forgetful and have had a little tightness in my stomach. I took a few hpt's but they all read negative. Help.